This invention is directed to anti-scald valves, and more particularly, anti-scald valves using a temperature responsive member for shutting of water flow at potentially harmful temperatures.
The prior art includes a variety of anti-scald valves directed to the prevention of burns via cutting of water flow at water temperatures which may be harmful to human tissue. As can be seen from the following descriptions, the prior art valves are generally complex in design and accordingly expensive to manufacture.
U.S. Pat. No. 4,262,844 to SeKiya discloses a control valve. The valve includes an inlet port 53 in communication with an outlet port 42 with a temperature responsive deflectable partition positioned therebetween. The partition is substantially ring-shaped having a portion of the inlet extending into a center hole therein. The partition extends above the outlet which comprises a plurality of radially extending grooves and a central hole. The central hole is in direct alignment with the inlet and the plurality of radially extending grooves are spaced in a circular formation around the central groove. The partition predetermined temperature for covering the circumferentially spaced radially extending grooves for substantially cutting off fluid flow through the valve. The specific structure of the valve, particularly the operation of the fluid flow closing partition, limits the partition, to being formed from a deflecting type temperature responsive material.
U.S. Pat. No. 5,259,554 to Ewing et al. discloses a shape memory effect actuated diaphragmatic anti-scald valve. The valve includes a shape memory effect leaf spring 36 supported in a slot (not shown) in a housing 15 and which passes into a slot 38 provided in pilot valve 40. A spring 44 is positioned in the valve 40 and provides a counteractive force against the leaf spring 36. Below a predetermined temperature, the leaf spring 36 is overcome by the force of spring 44 and the pilot valve is in the closed position as shown in FIG. 1, thereby allowing fluid flow through slot 17 of bore 19. As the temperature reaches a predetermined value, leaf spring 36 stiffens and returns to its flat position, overcoming the opposing force of spring 44. Accordingly, the pilot valve opens and unseats valve element 42 from the upper valve seat 23 to permit water flow through slots 25 in orifice 34 such that only a small amount of water continues to flow. Accordingly, while a stiffening shape memory element is incorporated, it is used to overcome a spring force which allows the main avenue of flow of the fluid through the valve to be cut off. In Ewing et al., the shape memory element is not directly linked with an element used to cause water flow cut-off.
U.S. Pat. No. 4,809,947 to Muntwyler discloses a flow regulation valve. The valve includes a heat responsive extension element 8 which extends substantially perpendicular to a gas line. The extension element 8 has a valve body 14 fastened to the center thereof and functions to maintain the valve body 14 against the valve seat 17 when the extension is not thermally activated. The extension element 8 is fastened on each end to covers 7 which are adapted to connect a current source which serves as a heating source for the extension 8. Upon heating the extension element 8 via the current, slight deflection of the extension element 8 occurs and thermal length variation of the extension element is transformed into an approximately 100-fold stroke of the valve body 14 relative to the valve seat 17. For this valve, the valve is closed during non-heated use; the extension is not a shape memory element but simply a strip of metal; and changes in valve position and fluid flow is not accomplished via stiffening but is accomplished by expansion.
In addition to the above patents, U.S. Pat. No. 4,402,455 to Kolt disclosing an automatic fluid control assembly; U.S. Pat. No. 4,480,780 to Bennett disclosing hot water cut-off safety valve for showers; U.S. Pat. No. 5,123,593 to Rundle disclosing a manual override heat sensitive valve; U.S. Pat. No. 4,778,104 to Fisher disclosing a temperature responsive line valve; and U.S. Pat. No. 3,450,344 to O'Brien disclosing a thermostatic valve for controlling the flow of fluids. Each represent valves having temperature responsive elements therein for effecting fluid flow. However, each of these valves are more complex than the valve of the instant invention and accordingly are less economically feasible than the valve of the present invention.
There exists, therefore, a need for a temperature responsive fluid flow valve for preventing scalding having a simple and economical design which safely cuts off fluid flow and which saves energy, which can be used in fluid flow applications such as, for example, with faucets and shower heads.